Microscopic Origin of Heisenberg and Non-Heisenberg Exchange Interactions in Ferromagnetic bcc Fe

By means of first principles calculations, we investigate the nature of exchange coupling in ferromagnetic bcc Fe on a microscopic level. Analyzing the basic electronic structure reveals a drastic difference between the 3d orbitals of E_{g} and T_{2g} symmetries. The latter ones define the shape of the Fermi surface, while the former ones form weakly interacting impurity levels. We demonstrate that, as a result of this, in Fe the T_{2g} orbitals participate in exchange interactions, which are only weakly dependent on the configuration of the spin moments and thus can be classified as Heisenberg-like. These couplings are shown to be driven by Fermi surface nesting. In contrast, for the E_{g} states, the Heisenberg picture breaks down since the corresponding contribution to the exchange interactions is shown to strongly depend on the reference state they are extracted from. Our analysis of the nearest-neighbor coupling indicates that the interactions among E_{g} states are mainly proportional to the corresponding hopping integral and thus can be attributed to be of double-exchange origin. By making a comparison to other magnetic transition metals, we put the results of bcc Fe into context and argue that iron has a unique behavior when it comes to magnetic exchange interactions.

Interatomic exchange interactions for finite-temperature magnetism and nonequilibrium spin dynamics

We derive ab inito exchange parameters for general noncollinear magnetic configurations, in terms of a multiple scattering formalism. We show that the general exchange formula has an anisotropiclike term even in the absence of spin-orbit coupling, and that this term is large, for instance, for collinear configuration in bcc Fe, whereas for fcc Ni it is quite small. We demonstrate that keeping this term leads to what one should consider a biquadratic effective spin Hamiltonian even in the case of collinear arrangement. In noncollinear systems this term results in new tensor elements that are important for exchange interactions at finite temperatures, but they have less importance at low temperature. To illustrate our results in practice, we calculate for bcc Fe magnon spectra obtained from configuration-dependent exchange parameters, where the configurations are determined by finite-temperature effects. Our theory results in the same quantitative results as the finite-temperature neutron scattering experiments.

Lactate production as a response to intrapartum hypoxia in the growth-restricted fetus

OBJECTIVE

To analyse whether the increase in lactate in response to intrapartum hypoxia differs between small- (SGA), appropriate- (AGA) and large-for-gestational-age (LGA) fetuses.

DESIGN

Observational cohort study.

SETTING

Ten obstetric units in Sweden.

POPULATION

A cohort of 1496 women.

METHODS

A secondary analysis of a randomised controlled trial, in which 1496 women with fetal heart rate abnormalities, indicating fetal scalp blood sampling, were randomised to lactate analyses. After delivery, the neonates were divided according to birthweight for gestational age into SGA, AGA and LGA groups.

MAIN OUTCOME MEASURE

Lactate concentration in fetal scalp blood.

SECONDARY OUTCOME MEASURES

Acid-base balance in cord artery blood and Apgar score <7 at 5 minutes.

RESULTS

Median lactate concentrations in the SGA, AGA and LGA groups were 3.8, 3.0 and 2.2 mmol/l, respectively (SGA versus AGA, P = 0.017; LGA versus AGA, P = 0.009). In the subgroups with scalp lactate >4.8 mmol/l (lactacidaemia), the corresponding median (range) values were 6.2 (4.9-14.6), 5.9 (4.9-15.9) and 5.7 mmol/l (5.0-7.9 mmol/l), respectively (no significant differences between the groups). The proportions of neonates with cord artery pH < 7.00, metabolic acidaemia or Apgar score <7 at 5 minutes were similar in all weight groups.

CONCLUSION

SGA fetuses with fetal heart rate abnormalities have the same ability to produce lactate as a response to intrapartum hypoxia as AGA and LGA fetuses. The risk of a poor outcome associated with high lactate concentration is the same in SGA, AGA and LGA fetuses. Scalp blood lactate analysis is therefore a reliable method for intrapartum fetal surveillance of suspected growth-restricted fetuses scheduled for vaginal delivery at ≥ 34 weeks of gestation.

Epitaxial Fe films on ZnSe(001): effect of the substrate surface reconstruction on the magnetic anisotropy

It is well known that Fe films deposited on a c(2 × 2)-reconstructed ZnSe(001) surface show a strong in-plane uniaxial magnetic anisotropy. Here, the effect of the substrate reconstruction on the magnetic anisotropy of Fe has been studied by in situ Brillouin light scattering. We found that the in-plane uniaxial anisotropy is strongly reduced for Fe films grown on a (1 × 1)-unreconstructed ZnSe substrate while the in-plane biaxial one is nearly unaffected by the substrate reconstruction. Calculations of magnetic anisotropy energies within the framework of ab initio density functional theory reveal that the strong suppression of anisotropy at the (1 × 1) interface occurs due to complex atomic relaxations as well as the competing effects originating from magnetocrystalline anisotropy and dipole-dipole interactions. For both sharp and intermixed c(2 × 2) interfaces, the magnetic anisotropy is enhanced compared to the (1 × 1) case due to the further lowering of symmetry. The theoretical results are in agreement with the experimental findings.

Determination of pH or lactate in fetal scalp blood in management of intrapartum fetal distress: randomised controlled multicentre trial

OBJECTIVE

To examine the effectiveness of pH analysis of fetal scalp blood compared with lactate analysis in identifying hypoxia in labour to prevent acidaemia at birth.

DESIGN

Randomised controlled multicentre trial.

SETTING

Labour wards.

PARTICIPANTS

Women with a singleton pregnancy, cephalic presentation, gestational age >or=34 weeks, and clinical indication for fetal scalp blood sampling.

INTERVENTIONS

Standard pH analysis (n=1496) or lactate analysis (n=1496) with an electrochemical microvolume (5 mul) test strip device. The cut-off levels for intervention were pH <7.21 and lactate >4.8 mmol/l, respectively.

MAIN OUTCOME MEASURE

Metabolic acidaemia (pH <7.05 and base deficit >12 mmol/l) or pH <7.00 in cord artery blood.

RESULTS

Metabolic acidaemia occurred in 3.2% in the lactate group and in 3.6% in the pH group (relative risk 0.91, 95% confidence interval 0.61 to 1.36). pH <7.00 occurred in 1.5% in the lactate group and in 1.8% in the pH group (0.84, 0.47 to 1.50). There was no significant difference in Apgar scores <7 at 5 minutes (1.15, 0.76 to 1.75) or operative deliveries for fetal distress (1.02, 0.93 to 1.11).

CONCLUSION

There were no significant differences in rate of acidaemia at birth after use of lactate analysis or pH analysis of fetal scalp blood samples to determine hypoxia during labour.

TRIAL REGISTRATION

ISRCT No 1606064.

Influence of ligand states on the relationship between orbital moment and magnetocrystalline anisotropy

The spin and orbital moments of Au/Co/Au trilayers grown on a W(110) single crystal substrate have been investigated by means of x-ray magnetic circular dichroism. Our findings suggest that the orbital moment of Co does not obtain a maximum value along the easy axis, in contrast with previous experience. This is attributed to the large spin-orbit interaction within the Au caps. Both second order perturbation theory and first principles calculations show how the magnetocrystalline anisotropy (MCA) is dramatically influenced by this effect, and how this leads to the fact that the orbital moment anisotropy is not proportional to the MCA.

First-principles approach to noncollinear magnetism: towards spin dynamics

A description of noncollinear magnetism in the framework of spin-density functional theory is presented for the exact exchange energy functional which depends explicitly on two-component spinor orbitals. The equations for the effective Kohn-Sham scalar potential and magnetic field are derived within the optimized effective potential (OEP) framework. With the example of a magnetically frustrated Cr monolayer it is shown that the resulting magnetization density exhibits much more noncollinear structure than standard calculations. Furthermore, a time-dependent generalization of the noncollinear OEP method is well suited for an ab initio description of spin dynamics. We also show that the magnetic moments of solids Fe, Co, and Ni are well reproduced.

Indications associated with increased cesarean section rates in a Swedish hospital

OBJECTIVE

To analyze the indications and Robson classes associated with the rapid increase in cesarean section (CS) rates at Söder Hospital, Stockholm, Sweden, in the late 1990s.

METHOD

Records of women who underwent CSs in 1994 and 1999 at Söder Hospital were retrospectively reviewed. Diagnostic frequency and Robson class, which takes into account characteristics such as parity, previous deliveries, prematurity, and fetal presentation, were compared for the 2 years.

RESULTS

Suspected fetal distress (+1.6%; P = .0001), maternal request (+1.5%; P < .0001), and labor dystocia (+0.8%; P = .03) were associated with the increase in CS rates. The rate of CSs with cephalic presentation and spontaneous onset of labor at term, as well as the rate of CSs following induced labor or elective CSs, increases significantly in both nulliparas and multiparas (Robson classes 1-4) (P < .02).

CONCLUSION

The increasing CS rate was due to maternal preference and lower thresholds of decision for physicians.

On the sharpness of the interfaces in metallic multilayers

We show that the three most relevant magnetic properties (magnetic moment, critical temperature, and interlayer exchange coupling) of metallic multilayers can be reproduced with good accuracy by first principles theory, provided that the picture of atomically sharp interfaces is abandoned and one allows instead for both interface alloying and interface roughness. The interface of a metallic multilayer (exemplified by the Fe/V system) is demonstrated to, at best, have interdiffusion essentially over two to three atomic layers on each side of the interface. Our conclusions are the result of combining experimental work with theoretical modeling, and we argue that this approach is the best avenue to obtain accurate information about the interface quality of metallic multilayers.

Origin of magnetic anisotropy of Gd metal

Using first-principles theory, we have calculated the energy of Gd as a function of spin direction, theta, between the c and a axes and found good agreement with experiment for both the total magnetic anisotropy energy and its angular dependence. The calculated low temperature direction of the magnetic moment lies at an angle of 20 degrees to the c axis. The calculated magnetic anisotropy energy of Gd metal is due to a unique mechanism involving a contribution of 7.5 microeV from the classical dipole-dipole interaction between spins plus a contribution of 16 microeV due to the spin-orbit interaction of the conduction electrons. The 4f spin polarizes the conduction electrons via exchange interaction, which transfers the magnetic anisotropy of the conduction electrons to the 4f spin.

Efficacy of epoetin beta on hemoglobin, quality of life, and transfusion needs in patients with anemia due to hormone-refractory prostate cancer--a randomized study

OBJECTIVE

Erythropoietin is shown to be an effective treatment for anemia in various types of cancers, however only limited studies have evaluated its benefits in advanced hormone-refractory prostate cancer (HRPC). This multi-center study investigated the influence of 2 different doses of epoetin beta on quality of life, hemoglobin level, need for blood transfusion, and safety, in the treatment of anemia in patients with metastatic HRPC.

MATERIALS AND METHODS

This study randomized 180 patients to receive either epoetin beta 1000 IU or 5000 IU subcutaneously 3 times per week for 12 weeks. Hemoglobin was evaluated at study start and 6 time-points during the study. Quality of life (QoL) was assessed by the European Organization for Research and Treatment of Cancer questionnaire, QLC-C30, before treatment start and after 6 and 12 weeks of treatment. Best supportive care and blood transfusions were given, if clinically indicated. Additional laboratory values and adverse events were followed for safety.

RESULTS

Hemoglobin increased significantly (>20 g/l) in 43% in the high dose (HD) group and 25% in the low dose (LD) group in response to treatment. Levels were significantly higher in the HD group than the LD group (p < 0.001) after 8 and 12 weeks. QoL improved significantly if the increase in hemoglobin was >20 g/l. Significantly more patients in the LD group received blood transfusions than the HD group (p < 0.005). There were no differences between the groups regarding overall quality of life and fatigue. The treatment was well tolerated in both groups.

CONCLUSIONS

Epoetin beta is shown to be safe and effective for the treatment of anemia in many patients with HRPC. It is found to improve QoL and physical functioning, and relieve fatigue symptoms, in many of these critically ill patients.

Preoperative treatment of anemic women with epoetin beta

AIM

To compare the effects of preoperative treatment with recombinant human erythropoietin (EPO) and iron with iron only on hemoglobin levels (Hb) in anemic women prior to hysterectomy.

METHODS

The study was an open-labelled randomized parallel study. Fifteen women scheduled for hysterectomy due to uterine myoma were given oral iron and EPO (NeoRecormon) 4 weeks prior to surgery (group I) and 16 women were given oral iron only (group II).

RESULTS

Group I showed a significantly greater increase in mean Hb during the pre-surgery study period compared with group II (p=0.007). Two weeks postoperatively, however, there was no significant difference in mean Hb between the two groups.

CONCLUSION

We found that a significantly greater increase in Hb was achieved with iron in combination with EPO, although in most cases iron only seemed to be as efficacious as iron+EPO in correcting anemia in myoma patients pre-operatively.

Preoperative treatment of anemic women with epoetin beta

AIM

To compare the effects of preoperative treatment with recombinant human erythropoietin (EPO) and iron with iron only on hemoglobin levels (Hb) in anemic women prior to hysterectomy.

METHODS

The study was an open-labelled randomized parallel study. Fifteen women scheduled for hysterectomy due to uterine myoma were given oral iron and EPO (NeoRecormon) 4 weeks prior to surgery (group I) and 16 women were given oral iron only (group II).

RESULTS

Group I showed a significantly greater increase in mean Hb during the pre-surgery study period compared with group II (p=0.007). Two weeks postoperatively, however, there was no significant difference in mean Hb between the two groups.

CONCLUSION

We found that a significantly greater increase in Hb was achieved with iron in combination with EPO, although in most cases iron only seemed to be as efficacious as iron+EPO in correcting anemia in myoma patients pre-operatively.

Lactate measurements in scalp and cord arterial blood

Lactate has been measured to evaluate fetal metabolic acidosis for some decades. However, not until the past few years have reliable lactate meters become available for bedside obstetric practice. The new technology, which requires only 5 microl blood, has reduced the sampling failure rate of fetal scalp blood to almost nil. A growing body of evidence has also shown lactate to be good at predicting neonatal outcome.

Warm tub bathing during labor: maternal and neonatal effects

AIM

To study possible detrimental maternal and neonatal effects of immersion in warm water during labor.

DESIGN

Prospective randomized controlled bathing during first stage of labor vs no bathing.

SETTING

Obstetrical departments at a university hospital and two central hospitals. PRIMARY END-POINT: Referral of newborns to NICU.

MATERIAL AND METHODS

Randomization took place by means of sealed opaque envelopes at each delivery unit. Preconditions for participation in the study were: singleton parturient wishing to bathe, a gestational duration of at least 35 weeks+0 days, a planned vaginal delivery, normal admission test, regular contractions and cervix dilated to at least 3-4 cm. Parturients randomized to the 'no bath' control group were allowed to use a shower. Rupture of the membranes was not a contra-indication to participation. Those excluded from randomization were women with intra-uterine growth retardation, meconium-stained amniotic fluid, or in the event that the tub was occupied by another randomized parturient.

MAIN RESULTS

On average, parturients stayed in the tub for 50-60 min. No significant difference was seen regarding the referral rate to NICU among 612 cases vs 625 controls, OR 0.8; 95% CL 0.2, 3.1. The OR for epidural analgesia was 1.0; 95% CL 0.8, 1.3. Nor was any significant difference seen in the rate of perineal tear grade III-IV (OR 1.3), instrumental delivery (OR 1.1), cesarean section (OR 1.8), or maternal post partum stay on the ward. During the neonatal period, no significant difference was seen in the number of newborns with Apgar <7 at 5 min (4 vs 5), neonatal distress (OR 2.2) or tachypnéa (OR 1.0).

CONCLUSION

In the present study no negative effects of bathing during labor could be discerned. The results indicate that expectant mothers wishing to bathe during labor may do so without jeopardizing their own, or their newborns' wellbeing after birth.

Fetal and maternal lactate increase during active second stage of labour

OBJECTIVE

To determine longitudinally fetal and maternal blood lactate concentrations during the second stage of labour.

DESIGN

Prospective, observational study of randomly selected labours.

SETTING

Labour ward, Sultanah Aminah General Hospital, Johore Bahru, Malaysia.

MAIN OUTCOME MEASURES

Fetal scalp and maternal venous blood lactate, umbilical arterial and vein lactate and acid-base balance at delivery.

RESULTS

Sixty-nine women and their infants were monitored in the second stage of labour. Mean maternal venous lactate by the end of the first stage was 2.6 +/- 1.0 (+/- S.D.) mmol/L and increased to 3.6 +/- 1.4, 4.2 +/- 1.7. 4.8 +/- 1.6, 5.4 +/- 2.1 and 4.3 +/- 0.9 mmol/L, respectively, for every 15 minute of bearing down. Corresponding values for fetal scalp blood lactate were 2.4 +/- 1.1, 3.1 +/- 1.6, 3.2 +/- 1.8, 4.2 +/- 2.4, 4.9 +/- 2.8 and 5.8 +/- 1.9 mmol/L. The mean slope of maternal lactate increase was 0.070 mmol/L per minute (95% CI 0.050, 0.090) and for fetal lactate increase 0.032 mmol/L per minute (95% C.I.: 0.018, 0.045). The duration of active second stage was significantly associated with fetal lactate (P < 0.001) and maternal lactate (P = 0.03) at the time of crowning of the fetal head, and lactate in umbilical arterial and vein blood at delivery (P < 0.001). Expulsion time > or = 45 minutes, compared with shorter active second stage, and acidaemia at birth implied larger arterial-venous lactate differences (P < 0.001). Fetal lactate at crowning was also significantly associated with the umbilical arterial-veonus lactate difference (P = 0.03).

CONCLUSIONS

Maternal and fetal lactate concentrations increase significantly with duration of the active second stage of labour, more rapidly in the mother. It is likely that fetal anaerobic metabolism is the main source for the fetal lactate increase.

Accidental falls and related fractures in 65-74 year olds: a retrospective study of 332 patients

We investigated, by studying medical records, background factors and consequences of accidental falls of patients 65-74 years who attended the Department of Orthopedics' emergency clinic in Lund. We also assessed possible prevention measures. Fractures occurred in three quarters of the registered falls. Women were more prone to sustain fractures than men. Forearm fractures were commonest among women while hip fractures were commonest among men. One third of the patients were admitted to an orthopedic ward because of the fall. The patients who were less healthy had sustained fractures oftener and also needed more hospital care. Information regarding risk factors for falls and fractures were often missing in the patients' medical records. Impaired walking and balance, and medication increased the risk of falls. Such patients constitute a high risk group for future falls and fractures. A newly developed instrument is suggested as a routine in the emergency department to increase the awareness of risk factors for falls in the elderly. Satisfactory documentation is a prerequisite for further treatment and referrals to prevent falls and fractures.

Intrapartum tocolysis has no effect on fetal lactate concentration

OBJECTIVE

To assess the fetal metabolic effects of intrapartum maternal tocolysis with terbutaline in the presence of fetal heart rate abnormalities, with a special emphasis on lactate concentration, in view of its potential use as a marker of fetal condition.

DESIGN

Descriptive study.

SETTING

Two labour wards, National University Hospital, Singapore, and Ostersund Hospital, Sweden.

METHODS

Eight parturients with abnormal intrapartum fetal heart rate recordings were given bolus i.v. injection of 0.25 mg terbutaline and monitored both before and 20 minutes after treatment.

RESULTS

Maternal venous glucose increased from 5.0 (0.9) (mean (SD)) to 5.6 (1.2) mmol/l (p=0.002) and fetal scalp blood glucose rose from 4.1 (1.8) to 4.7 (1.4) mmol/l (p=0.009) 20 minutes after the injection. No significant change was found in maternal or fetal lactate concentrations.

CONCLUSION

Terbutaline tocolysis for "intrauterine resuscitation" does not affect fetal lactate concentration 20 minutes after treatment.

Umbilical artery blood gas and lactate in healthy newborns

This study aimed to establish the normal range of umbilical artery pH, pCO2, base deficit and lactate in normal term and preterm newborn. Umbilical artery pH, pCO2, base deficit and lactate was measured in 637 newborn babies. The study included 555 babies at term with Apgar score equal to or more than 7 at 5 minutes, not requiring assisted ventilation and not admitted to the neonatal unit (NNU), as well as 47 preterm babies with Apgar score equal to or more than 7 at 5 minutes who were admitted to the NNU for observation only because of prematurity. Data was presented as mean and SD. Statistical analysis was done by t-test and simple linear regression analysis. In the newborn at term mean umbilical artery blood gas and lactate were as follows; pH = 7.25 (+/- 0.08), pCO2 = 45.66 (+/- 1.88) mmHg, base deficit = 7.69 (+/- 3.88) mEq/L, lactate = 2.96 (+/- 1.8) mMol/L. In preterm newborn the values were; pH = 7.25 (+/- 0.04), pCO2 = 51.78 (+/- 13.00) mmHg, base deficit = 5.29 (+/- 1.87) mEq/L, lactate = 2.55 (+/- 1.87) mMol/L. The range of umbilical artery blood gas and lactate parameters in term and preterm fetuses with good neonatal outcome were derived. There was a statistically significant difference in pCO2 and base deficit between term and preterm newborn. There was no linear correlation between lactate, pH, pCO2, base deficit and fetal glucose respectively in term or preterm infants.

Transient fetal cerebral dysfunction after road traffic accident. A case report

We present a case at 30 weeks gestation with transient abnormal fetal cerebral function after a road traffic accident, with loss of fetal movements and abnormal FHR tracings for almost 1 week. The pregnancy had after this incident a normal course and a healthy baby boy was born at term. We suggest the mechanism to be related to fetal hypoxia after excessive maternal psychological stress.

Intrapartum fetal hypoxia and biochemical markers: a review

Intrapartum fetal hypoxia is a rare event, although fetal intrapartum surveillance is discussed as a subject of major importance. This is mainly because of consequences of fetal hypoxia that may lead to cerebral palsy. A fetus suffering from hypoxia initially compensates by producing energy through anaerobic metabolism. At some stage, the fetus becomes decompensated and basic cellular functions fail, with risks of permanent morbidity or mortality. How long a fetus can survive on anaerobic metabolism differs because metabolic reserves differ, i.e., growth-restricted fetuses might deteriorate at an earlier stage. An increasing body of evidence has clarified brain-damaging mechanisms. Neuronal loss occurs in two phases: during the primary hypoxic event and later during the reperfusion/reoxygenation phase. Animal studies have suggested the possibility of prophylactic treatment to prevent neuronal loss after the hypoxic event. Intrapartum diagnostic tools should aim for detecting fetal hypoxemia/hypoxia when the fetus is still compensated. This may be achieved by assessment of biochemical data such as pH, lactate, and oxygen saturation, with the aim of prophylactic intervention before the fetus becomes decompensated. The measurement of cord blood levels of oxygen free radicals and excitatory amino acids at the time of birth may prove to be helpful in determining the risk of brain damage and evaluating the effect of prophylactic treatments to prevent or ameliorate brain injury from hypoxia.

Lactate, lactate/pyruvate ratio and catecholamine interrelations in cord blood at delivery in complicated pregnancies

The interrelationships between lactate, lactate/pyruvate (L/P) ratio and catecholamines (CA) in cord artery and vein blood were studied in 56 pregnancies who had complications in the antenatal period or during labour. This group of babies had higher CA levels and were more acidaemic than fetuses after normal pregnancies and labour. There were stronger correlations between lactate and noradrenaline (NA) (R = 0.56, P < 0.001), adrenaline (A) (R = 0.41, P = 0.002) and dopamine (DA) (R = 0.42, P = 0.001) in cord artery blood, than previously reported for normal deliveries. Correlations between L/P ratio and CAs were also significant, although weaker. Multiple regression analysis, using cord artery lactate as the dependent variable, revealed significant correlations for pH (P = 0.01) and pyruvate (P < 0.001) but not for the CAs. The subgroups with high lactate (> 75th centile) had significantly higher NA (P = 0.007) and DA (P < 0.001) in cord artery and NA (P < 0.001) and A (P < 0.001) in cord vein blood, as compared with the subgroup who had lower lactate concentrations. We conclude that fetal hypoxia induces fetal CA production as well as anaerobic metabolism with lactate production. However, the adrenergic stimulation seems not to contribute significantly to the fetal lactate production.

Quality assessment of two lactate test strip methods suitable for obstetric use

Accuracy of lactate determinations in cord blood was tested for one reflectometric (Accusport) and one amperometric (Lactate Pro) microvolume test strip lactate meter. Both meters, using a whole blood sample, measure lower levels of lactate than a reflectometric device considered as a reference method, which analyses lactate in plasma. Readings were unaffected irrespective of lactate concentrations for the Lactate Pro, whilst the Accusport overestimated low lactate concentrations and underestimated high values. Both lactate meters underestimated lactate concentrations at high hematocrits, as compared with the reference method. The Lactate Pro has a fixed sample volume of 5 microliters while the Accusport uses random blood drop as sample volume. However, in analyses with less than 20 microliters sample volume considerable underestimation was found with the Accusport. Coefficient of variation was 3.8-8.9% for the Accusport and 3.1-4.0% for the Lactate Pro within lactate concentrations between 2.1 and 5.3 mmol/l. The amperometric device, the Lactate Pro, performed best in these tests dealing with fetal blood lactate concentrations. The new technique can be a useful tool in perinatal research as well as in obstetric practice.

[Parturients are under-treated. Only 21 out of 55 clinics administer oxytocics routinely during the third stage of labor]

A questionnaire answered by all 55 Swedish labour wards in 1995 showed oxytocic treatment to be given routinely to all parturients during the third stage of labour at only 38% (21/55) of the units, and that five of these 21 units were considering cessation of the practice. At a further 25 units the treatment was given routinely only in selected risk cases, the most common risk factors being a history of postpartum haemorrhage (a criterion at 20 units), multiple pregnancy (14 units), prolonged labour (12 units), and a large baby (8 units). Of the remaining nine units, where oxytocic treatment was given only on clinical indications (i.e., postpartum haemorrhage), two were considering the introduction of routine treatment. In view of results obtained in a recent randomised, placebo controlled Swedish study, the authors of the article conclude that, if clinical practice in this respect has remained unchanged since the questionnaire study was performed, Swedish parturients are undertreated with oxytocics during the third stage of labour.

Metabolic control and pregnancy outcome among women with insulin-dependent diabetes mellitus. A twelve-year follow-up in the country of Jämtland, Sweden

OBJECTIVE

To assess metabolic control and pregnancy outcome in women with insulin-dependent diabetes mellitus (IDDM) in a defined rural area of Sweden and to compare results for three four-year periods (1982-85, 1986-89, 1990-93).

MATERIAL AND METHOD

All pregnancies in women with IDDM during the 12-year period, 1982-93, received their antenatal care from a 'diabetic team' at the County Hospital, Ostersund. There were 50 women in the series, accounting for a total of 91 pregnancies. Spontaneous or induced abortions occurred in 19 cases. Case notes from maternity, neonatal and pediatric care were retrospectively scrutinized.

RESULTS

In period one 31% of the pregnancies occurred in gravidae with diabetes classified as White D, F or R, as compared with 46% and 71% during periods two and three (p=0.001). Maternal hypertension was also more frequent in period three (12%, 26% and 54%, respectively; p=0.001). Fewer antenatal admissions (p=0.02) but more frequent ultrasound scannings (p=0.014) were recorded for period three. HbA1c levels decreased continuously from prepregnancy through first and third trimesters (9.7%, 8.4%, and 7.4%, respectively; p<0.0001). Perinatal mortality and frequencies of congenital malformations were both 4.2% (95% CI 0.5-8.8%), whereas the miscarriage rate was 14.3% (95% CI 6.8-21.8%).

CONCLUSIONS

As compared with the first 4-year period, 1982-85, the third period, 1990-93, was characterized by a greater proportion of gravidae with more serious diabetes and a higher rate of pregnancy complications, though the outcome was nonetheless good, suggesting the diabetic pregnancy care program to have been efficacious.

Transient fetal cerebral dysfunction after road traffic accident. A case report

We present a case at 30 weeks gestation with transient abnormal fetal cerebral function after a road traffic accident, with loss of fetal movements and abnormal FHR tracings for almost 1 week. The pregnancy had after this incident a normal course and a healthy baby boy was born at term. We suggest the mechanism to be related to fetal hypoxia after excessive maternal psychological stress.

Lactate and acid-base balance at delivery in relation to cardiotocography and T/QRS ratios in the second stage of labour

OBJECTIVE

To compare foetal electrocardiogram (T/QRS ratio) and cardiotocography (CTG) during the second stage of labour with lactate and acid-base balance in cord artery blood at delivery.

DESIGN

Forty-six parturients delivered at the National University of Singapore were monitored during the second stage of labour with T/QRS ratios and CTG. At delivery blood from a segment of clamped cord was sampled for lactate and acid-base balance analyses. The Spearman Rank correlation, the Mann Whitney U-test and the Kruskal Wallis ANOVA were used when appropriate.

RESULTS

Maternal pushing time was significantly correlated to lactate (R = 0.51; P = 0.0003), pH (R = -0.38; P = 0.009) and base deficit (R = 0.33; P = 0.026), but not to T/QRS ratio (R = 0.002; P = 0.99). No significant correlation between lactate and T/QRS ratios (R = 0.06; P = 0.70) or type of CTG pattern was found (P = 0.10), though there were significant differences in pH (P = 0.029) and T/QRS ratios (P = 0.037) between groups with different FHR abnormalities.

CONCLUSION

Lactate increases progressively with maternal pushing time. No significant correlation was found between lactate and the T/QRS ratio. Lack of correlation is likely to be due to poor sensitivity of foetal ECG at this level of foetal stress, though the influence from transplacentally transferred maternal lactate cannot be excluded.

Preoperative autologous donation of 6 units of blood during rh-EPO treatment

PURPOSE

To determine if donation of six units of blood in three weeks is possible with self-administered subcutaneous recombinant human erythropoietin (rhEPO) injections and oral iron treatment.

METHODS

A prospective trial where a total of 32 otherwise healthy patients were phlebotomised before revision hip arthroplasty during rhEPO and oral iron treatment (ferrofumarate). Adverse events were noted and compliance was controlled. Routine laboratory tests were performed at each visit including reticulocytes and 2,3-DPG. The relative oxygen releasing capacity (RORC) and the oxygen releasing capacity (ORC) were calculated. Blood donation was postponed until the next visit if haemoglobin concentrations was < 115 g.l-1 (men) or < 105 g.l-1 (women).

RESULTS

All but two patients were able to donate six units of blood with an acceptable haemoglobin concentration on the day of operation. One serious adverse event occurred when the Hb was 119 g.l-1, compared with 149 g.l-1 before treatment. During the first two weeks before phlebotomy there was no increase in Hb, the mean nadir was reached after six phlebotomies (31 g.l-1 below pre-study level), while at operation it was 19 g.l-1 below pre-study level. There was an increase in 2,3-DPG and oxygen releasing capacity after the initiation of rhEPO therapy, before the first phlebotomy.

CONCLUSION

It is possible to donate six units of blood in a three week period before surgery during self-administered subcutaneous rhEPO treatment and oral iron therapy at a rhEPO dose of 60 U.kg-1 BW three times a week. It is suggested that rhEPO per se initiates a right-shift of the oxygen dissociation curve via an increased 2,3-DPG level, which could explain that some patients report subjective benefit of rhEPO in spite of no change in Hb concentration.

Routine oxytocin in the third stage of labour: a placebo controlled randomised trial

OBJECTIVE

To compare intravenous oxytocin administration (Partocon 10 IU) with saline solution in the management of postpartum haemorrhage in the third stage of labour.

DESIGN

A double-blind, randomised controlled trial involving 1000 parturients with singleton fetuses in cephalic presentation and undergoing vaginal delivery, randomly allocated to treatment with oxytocin (n = 513) or 0.9% saline solution (n = 487).

SETTING

Labour ward at a central county hospital.

MAIN OUTCOME MEASURES

Mean blood loss (total, and before and after placenta delivery); frequencies of blood loss > 800 mL, need of additional oxytocic treatment, postpartum haemoglobin < 10 g/dL; and duration of postpartum hospitalisation.

RESULTS

As compared with saline solution, oxytocin administration was associated with significant reduction in mean total blood loss (407 versus 527 mL), and in frequencies of postpartum haemorrhage > 800 mL (8.8% versus 5.2%), additional treatment with metylergometrine (7.8% versus 13.8%), and postpartum Hb < 10 g/dL (9.7% versus 15.2%), and a nonsignificant increase in the frequency of manual placenta removal (3.5% versus 2.3%). There was no group difference in the mean duration of postpartum hospitalisation (4.6 versus 4.5 days, respectively).

CONCLUSIONS

Administration of intravenous oxytocin in the third stage of labour is associated with an approximately 22% reduction in mean blood loss, and approximately 40% reductions in frequencies of postpartum haemorrhage (> 500 mL or > 800 mL) and of postpartum haemoglobin < 10 g/dL. Identification of risk groups for oxytocin treatment does not seem worthwhile. Oxytocin is a cheap atoxic drug and should be given routinely after vaginal delivery.

Studies of mice lacking plasminogen activator gene function suggest that plasmin production prior to ovulation exceeds the amount needed for optimal ovulation efficiency

Many studies suggest that the plasminogen activator (PA) system plays a role in the proteolytic degradation of the follicle wall at the time of ovulation. Consistently, the ovulation efficiency is reduced by 26% in mice where both physiological PA genes have been inactivated. To reveal the mechanism behind reduced ovulation efficiency in PA-deficient mice and its effect on ovarian proteolysis. we have studied the regulation of plasmin activity in the ovaries of 25-day-old wild-type mice and mice with deficient PA gene function during gonadotropin-induced ovulation. In wild-type mice the plasmin activity was low in ovarian extracts from mice treated with pregnant mare's serum gonadotropin. However, this activity was increased between 2-8 h after an ovulatory dose of human choriogonadotropins. In mice lacking either tissue-type PA (tPA) or PA inhibitor type 1 (PAI-1) the plasmin activity levels prior to ovulation were similar to wild-type mice, while extracts prepared from urokinase-type PA (uPA) deficient mice had 10% or less of the plasmin activity. This indicates that most of the plasmin activity in the mouse ovary is generated by uPA. In addition, as the ovulation efficiency is impaired in tPA/uPA-deficient mice but appears normal in uPA-deficient mice, our data indicates that the amount of plasmin generated by PAs prior to ovulation in wild-type mice greatly exceeds the amount required for efficient ovulation.

A delivery system for inhalation of nitric oxide evaluated with chemiluminescence, electrochemical fuel cells, and capnography

OBJECTIVE

To evaluate a system for delivery of inhaled nitric oxide.

DESIGN

Prospective, laboratory study.

SETTING

Engineering laboratory.

SUBJECTS

A standard ventilator (Servo Ventilator 300), supplemented with extra gas modules for nitric oxide delivery.

INTERVENTIONS

Two ventilator-integrated gas modules, delivering < or = 10 parts per million (ppm) or < or = 100 ppm of nitric oxide, were used in adult and neonatal modes during volume-controlled ventilation. Set nitric oxide concentration and FIO2 were systematically changed and compared with the measured concentration. Short-term mixing was tested in adult, pediatric, and neonatal modes by substituting nitric oxide with CO2, and measuring the delivered concentration by a fast-response CO2 analyzer during five successive respiratory cycles. Long-term mixing was tested with the administration of 25 ppm of nitric oxide for 7 days.

MEASUREMENTS AND MAIN RESULTS

Delivered concentration of nitric oxide and nitrogen dioxide were simultaneously measured at the Y-place by two methods-chemiluminescence and electro-chemical fuel cells. The maximum absolute difference between set and measured concentrations of nitric oxide in the adult mode was 0.6 ppm at a set concentration of 10 ppm and 2.7 ppm at a set concentration of 100 ppm. In the neonatal mode, the maximal difference was 3.1 ppm at a set concentration of 100 ppm. Nitrogen dioxide concentration increased with increasing concentration of nitric oxide and oxygen to 2.6 ppm (as measured by the chemiluminescence analyzer) and 3.6 ppm (as measured by the electro-chemical fuel cell), at a setting of 100 ppm of nitric oxide with an FIO2 of 0.90 in the neonatal mode (2 L/min). During the short-term test of mixing stability throughout the respiratory cycles, a constant set CO2 concentration varied maximally by +/-6.2% from the set value in the neonatal mode, whereas the variance was by +/-6.5% in pediatric mode, and by +/-8.0% in the adult mode. During the long-term test, nitric oxide concentration varied maximally by +/-2.6% (as measured by the chemiluminescence analyzer) and by +/-2.3% (as measured by the electrochemical fuel cell).

CONCLUSIONS

An accurate precision in delivered nitric oxide concentration was achieved during intermittent flow ventilation, and this accuracy was independent of tested ventilator settings. The delivery system administered an almost stable concentration throughout a respiratory cycle and during long-term delivery. If the mixing point is in the inspiratory part of the ventilator, valid measurement of nitric oxide and nitrogen dioxide delivery concentrations are possible. Both techniques for measuring nitric oxide and nitrogen dioxide have drawbacks.

Lactate in cord blood and its relationship to pH and catecholamines in spontaneous vaginal deliveries

The interrelationships between lactate and pH, nonadrenaline (NA), adrenaline (A) and dopamine (DA) were investigated in cord artery (CA) and vein (GV) blood at delivery. Sixty consecutive, spontaneous, vaginal deliveries with fetuses in cephalic presentation were assessed. Median gestational age at delivery was 40 weeks (range, 35-43). There were significant correlations between lactate and pH (P < 0.01), NA (P < 0.01), A (P < 0.05) and arterio-venous NA (P < 0.05) and DA differences (P < 0.01) in CA blood, while no variable correlated significantly to lactate in CV blood. The higher levels both of lactate and of catecholamines in CA blood are probably fetally derived. Dividing the material into high and low lactate subgroups (cut-off level, 75th percentile) showed a high lactate level to be associated with lower pH and higher catecholamine levels in CA blood, though the relationship was only statistically significant for pH. The levels both of catecholamines and of lactate were lower than those reported for cases of fetal distress, and reflect the lower level of fetal stress in the present series of normal deliveries. The low level of fetal stress and the differences in turnover rates between catecholamines and lactate might obscure their causal relationships, vis-a-vis fetal adaptation to extrauterine life during the course of parturition.

Fetal monitoring with lactate

Lactate is a metabolite that can safely and easily can be determined in fetal scalp blood using new microvolume (5-20 microliters) lactate meters. However, new lactate analysing methods need their own reference values. There are factors other than hypoxia that might increase fetal lactate levels, although this does not disqualify this parameter for intrapartum surveillance. Available data on fetal lactate determination give support that it can simplify FBS in labour and is likely to predict fetal tissue hypoxia at least as well as is pH determination. Prospective randomized studies are needed before the method can be introduced into clinical practice. As a predictor of neonatal outcome, lactate can substitute pH in routine assessment of cord artery blood at delivery.

Ovulation efficiency is reduced in mice that lack plasminogen activator gene function: functional redundancy among physiological plasminogen activators

Several lines of indirect evidence suggest that plasminogen activation plays a crucial role in degradation of the follicular wall during ovulation. However, single-deficient mice lacking tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), or PA inhibitor type 1(PAI-1) gene function were recently found to have normal reproduction, although mice with a combined deficiency of tPA and uPA were significantly less fertile. To investigate whether the reduced fertility of mice lacking PA gene function is due to a reduced ovulation mechanism, we have determined the ovulation efficiency in 25-day-old mice during gonadotropin-induced ovulation. Our results reveal that ovulation efficiency is normal in mice with a single deficiency of tPA or uPA but reduced by 26% in mice lacking both physiological PAs. This result suggests that plasminogen activation plays a role in ovulatory response, although neither tPA nor uPA individually or in combination is obligatory for ovulation. The loss of an individual PA seems to be functionally complemented by the remaining PA but this compensation does not appear to involve any compensatory up-regulation. Our data imply that a functionally redundant mechanism for plasmin formation operates during gonadotropin-induced ovulation and that PAs together with other proteases generate the proteolytic activity required for follicular wall degradation.

Scalp blood lactate: a new test strip method for monitoring fetal wellbeing in labour

OBJECTIVE

To determine fetal scalp blood lactate with a new test strip method in parturients with normal and abnormal cardiotocograms during labour and to describe the relation to maternal lactate, fetal scalp blood pH, cord artery lactate and acid-base balance.

SETTING

Labour wards at the University Hospitals of Huddinge and Lund and at the County Hospital of Ostersund, Sweden.

MATERIALS AND METHOD

Fetal scalp blood was sampled for lactate (n = 269) and pH (n = 285) determination in 177 parturients with abnormal intrapartum CTG. Lactate and pH were also analysed in a group of 64 women with normal pregnancies and with a reactive fetal heart rate tracing prior to sampling of fetal scalp blood. At fetal blood sampling lactate was also determined in maternal capillary blood, while at birth lactate and acid-base balance in cord artery blood was performed in almost all cases.

MAIN OUTCOME MEASUREMENTS

Medians and percentiles (lactate and acid-base balance). Correlation between fetal scalp blood lactate (dependent) and scalp blood pH, cord artery blood lactate and acid-base parameters and labour time prior to fetal blood sampling.

RESULTS

In the group with abnormal cardiotocograms, fetal scalp and umbilical artery blood lactate and acid-base parameters differed significantly from the same parameters in the normal group. The fetal-maternal lactate gradient changed from negative in the normal group to positive in the fetal distress group. Multiple regression analysis, with scalp lactate as the dependent parameter, revealed a significant correlation with fetal scalp blood pH (P < 0.001) and umbilical artery lactate (P < 0.01).

CONCLUSIONS

Intrapartum scalp blood lactate was significantly correlated with pH and cord artery lactate. The results indicate that increased lactate levels in fetal blood sampling describes fetal lactacidosis. The new disposable test strip requiring only 5 microliters of blood for lactate determination may be better than traditional methods for monitoring fetal wellbeing in labour.

Routine measurements of umbilical artery lactate levels in the prediction of perinatal outcome

OBJECTIVE

Our purpose was to compare lactate levels with acid-base balance in the umbilical artery with respect to the prediction of pregnancy outcome.

STUDY DESIGN

A prospective study of 4045 cord samples was performed. Lactate was measured with a new method that requires 5 microliters of blood and provides the result within 1 minute.

RESULTS

The umbilical artery lactate concentrations were significantly elevated in instrumental deliveries (2.65 +/- 1.2 mmol/L) and in emergency cesarean sections (2.44 +/- 1.7 mmol/L) compared with spontaneous vaginal delivery (1.87 +/- 0.94 mmol/L) (p < 0.001, p < 0.001). Lactate correlated significantly to fetal pH, hemoglobin, base deficit, PCO2, and HCO3-. Lactate was comparable to pH and base deficit in sensitivity, specificity, and positive and negative predictive values in relation to morbidity and mortality.

CONCLUSION

Umbilical artery lactate concentration and acid-base balance predicted perinatal outcomes with similar efficacies; however, its simplicity makes lactate analysis an interesting alternative in obstetric care.

Continuous maternal glucose infusion during labor: effects on maternal and fetal glucose and lactate levels

Fetal and neonatal glucose and lactate levels and acid-base balance after continuous maternal infusion of 5% dextrose at 180 mL/h (9 g/h) was compared with 0.9% saline solution in a prospective, randomized study from selected monitored labors. An infusion of 5% dextrose produced significantly increased glucose levels in maternal (p < 0.01), cord artery (p < 0.01), and cord vein (p < 0.001) blood. An increased maternal insulin level was also present (p < 0.05), but no differences in cord insulin levels were observed. beta-Hydroxybutyrate was lower in maternal (p < 0.05) and cord vein (p < 0.01), but not in cord artery blood, after maternal dextrose infusion. No significant changes occurred in blood lactate levels between the two groups in either mother, fetus, cord, or neonate. Acid-base balance in cord blood did not differ between the two groups. Maternal infusion of 5% dextrose at 180 mL/h (9 g/h), compared with saline solution, produces higher glucose levels in both mother and fetus, but increased insulin concentrations only in the mother. Dextrose infusion also lowers beta-hydroxybutyrate in maternal and cord vein blood. No differences were seen in lactate levels or cord acid-base balance. Both regimens seem safe according to risks for lactacidosis and neonatal hypoglycemia in the normoxemic, normal size fetus.